JP2017194885A - Underwater Sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve reduction in power consumption of an underwater sensor.SOLUTION: An underwater sensor includes: a sensor unit; a transmission signal processing unit for transmitting measurement data by the sensor unit as an underwater ultrasonic wave; a reception signal processing unit that receives the underwater ultrasonic wave and includes a frequency discrimination circuit for determining whether a frequency of a reception signal virtually accords with a prescribed frequency; and a control unit that is supplied with a determination result by the reception signal processing unit and performs control to start the transmission signal processing unit if the frequency of the reception signal virtually accords with the prescribed frequency.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an underwater sensor installed in water and applied to measure water quality, water depth, and the like.

  For example, a CTD (electric conductivity (salt content), water temperature, depth meter) is known as a large-scale collection device as a device for measuring the temperature, depth, etc. of seawater. A CTD is connected to a cable from an observation ship (investigation ship) and dropped into the sea, and the distribution of salinity and water temperature in the depth direction is measured. The characteristics and flow of seawater are analyzed based on the measurement data.

  Since CTD is large and expensive, underwater sensors that are smaller and cheaper are used on fishing boats and the like. The underwater sensor has various sensors mounted in a cylindrical case, stores measurement data in a built-in memory, and reads the measurement data in the memory with a dedicated reader after collection.

  In the case where the measurement data is stored in the memory, there is a problem that the water temperature cannot be known in real time. For example, Patent Document 1 describes that a cable is not required and the obtained measurement data is transmitted to the main station on the ship by underwater ultrasonic waves in real time.

Japanese Patent Laid-Open No. 2002-9709

  In the configuration shown in Patent Document 1, during use, the maritime station on the ship and the underwater sensor (transmission / reception station) in the sea are continuously communicating with each other, and there is a problem that the battery is consumed heavily. In consideration of being disposable, it is desirable that the usable period of the underwater sensor is one year or longer. As one of power saving methods, it is conceivable to set the underwater sensor to a resting state when not measuring and to operate the underwater sensor only during measurement. However, when the underwater sensor operates and transmits its own measurement data, it is difficult to collect measurement data reliably because the ship carrying the maritime station that receives the measurement data is not always nearby. There is.

  Accordingly, an object of the present invention is to provide an underwater sensor that can reliably collect measurement data of the underwater sensor, consume less power, and extend the usable period.

The present invention includes a sensor unit, a transmission signal processing unit that transmits measurement data of the sensor unit as underwater ultrasonic waves,
A received signal processing unit having a frequency discrimination circuit that receives underwater ultrasonic waves and determines whether or not the frequency of the received signal substantially matches a predetermined frequency;
And a control unit that performs control such that the transmission signal processing unit is activated when the reception signal processing unit is supplied with the determination result and the frequency of the reception signal substantially matches a predetermined frequency.

  According to the present invention, when a predetermined underwater ultrasonic wave is received, the transmission signal processing unit is activated to perform measurement, so that power consumption can be reduced and the usable period of the apparatus can be extended. Furthermore, since it can be ensured that a vessel such as a fishing boat or a survey vessel is nearby, there is an advantage that the transmission of measurement data is not wasted. Note that the effects described here are not necessarily limited, and this specification Any of the effects described therein may be used.

It is a basic diagram used for description of the outline of the measuring system of this invention. It is a block diagram which shows the electric constitution of an underwater sensor. It is a wave form diagram used for description of one embodiment. It is a flowchart for demonstrating one embodiment. It is a block diagram which shows an example of a receiver.

Embodiments of the present invention will be described below. The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is not limited to the following description. Unless otherwise specified, the present invention is not limited to these embodiments.
The description of the present invention will be made in the following order.
<1. Embodiment>
<2. Modification>

<1. Embodiment>
FIG. 1 shows an outline of a measurement system according to an embodiment. For example, an underwater sensor 1 is installed in the sea. A weight is attached to the underwater sensor 1 so that the position of the underwater sensor 1 does not change as much as possible. The underwater sensor 1 may be attached to a fishing gear such as a structure such as a fish reef, a fishing net, and a crab other than being placed on the seabed. The underwater sensor 1 includes a sensor unit for measuring water depth, water temperature, water quality (salin concentration, oxygen concentration, etc.), a communication unit for transmission / reception with a transmitting / receiving device on a ship, a power source unit such as a battery, and the like. A storage unit for storing data is provided.

  Measurement data obtained by the underwater sensor 1 is transmitted to the maritime station as an underwater acoustic wave signal. For example, a maritime station is loaded on the fishing boat 2. The maritime station includes a transmitter for transmitting underwater sound waves, a wave receiver for receiving underwater sound waves, and a communication unit. The maritime station can communicate with the land station via communication such as the Internet. An observation boat may be used instead of the fishing boat 2. However, since the number of observation boats is limited, it is practical to install a maritime station on the fishing boat 2 with the cooperation of fishermen in order to obtain ocean data in a wide range of sea areas.

  The fishing boat 2 is usually equipped with a fish finder. A fish finder is an electronic device for fisheries that can detect the existence of a school of fish, the depth of water, the topography of the seabed, etc. by emitting ultrasonic waves in the water and capturing the reflected waves. Fish finders use several types of ultrasonic frequencies. The frequency is switched as necessary. As an example, ultrasonic waves having a frequency in the range of 30 to 400 kHz are used.

  The underwater sensor 1 on the seabed can receive underwater ultrasonic waves (referred to as detection beams as appropriate) 3 from the fish finder of the fishing boat 2. When the underwater sensor 1 is not receiving the detection beam 3 (the state shown in FIG. 1A), the underwater sensor 1 is set to the power saving mode. The power saving mode is a state in which only a component for receiving the detection beam of the fish detector and activating the underwater sensor 1 is operating.

  On the other hand, as shown in FIG. 1B, when the underwater sensor 1 receives a detection beam, the power saving mode is switched to the operation mode. The operation mode is a function for measuring the water temperature, etc., a function for processing the measurement data, a communication function for transmitting the measurement data to the maritime station, and a component for operating the power saving mode after completing the transmission of the measurement data. It is.

  The underwater sensor 1 is installed in advance by a survey boat and a fishing boat, and the installation position is recorded and stored. For example, the underwater sensor 1 is dropped with weights at a plurality of locations in the operating sea area of the fishing boat 2 and the installation position is checked by receiving ultrasonic waves from the underwater sensor 1 immediately after dropping. Accordingly, the detection beam 3 of the fish finder can reach the underwater sensor 1 when the fishing boat 2 is subsequently operating in the operating sea area. Furthermore, instead of the detection beam 3, the underwater sensor 1 may respond to a predetermined transmission beam of the maritime station and switch between the power saving mode and the operation mode. However, it is practical to use the detection beam 3 of the fish finder for the activation of the underwater sensor 1.

  The underwater sensor 1 includes a circuit unit mounted on a printed circuit board in a cylindrical resin case, a primary battery as a power source, for example, a lithium ion primary battery, and the case is filled with an epoxy resin. Projected from one end of the case are a sensor (for example, a temperature sensor, a pressure sensor as a depth sensor) and an ultrasonic transducer for emitting ultrasonic waves into water and receiving ultrasonic waves in water. A large capacity capacitor may be used instead of the primary battery.

  An electrical configuration of an example of the underwater sensor 1 is shown with reference to FIG. A CPU (Central Processing Unit) 11 that controls the overall operation of the underwater sensor 1 is provided. Although not shown, the CPU 11 constitutes a microprocessor together with a RAM (Random Access Memory), a ROM (Read Only Memory) and the like. A memory 12 is connected to the CPU 11. The memory 12 stores measurement data acquired by the underwater sensor 1 or data obtained by performing processing such as noise removal on the measurement data. When the underwater sensor 1 is lifted from the sea, the data in the memory 12 is read through a wired interface or a wireless interface by a marine or land station device.

  A detection signal from the sensor 13 is supplied to the A / D converter 15 via the sensor amplifier 14 and converted into digital data having a predetermined number of bits. Output data of the A / D converter 15 is supplied to the CPU 11 for processing. Switches SW1, SW2 and SW3 for turning on / off the power supply of the sensor 13, the sensor amplifier 14 and the A / D converter 15 are provided. A battery (for example, a lithium ion primary battery) 16 is used as a power source. These switches SW1 to SW3 are controlled by a control signal from the CPU 11. A transmission signal processing unit and a reception signal processing unit are provided for the CPU 11.

  The transmission signal processing unit includes a gold code signal generator 17, a transmission amplifier 18, and a transmitter 19. The Gold code is one of PN (Pseudorandom Noise) series. As an example, a transmission signal obtained by phase-modulating a carrier signal with a predetermined number of bits of a Gold code is formed. A plurality of types of gold codes, for example, 32 types of gold codes are used. The gold code represents the type of transmission data and the ID for identifying the underwater sensor. The data value is represented by an interval of transmission data, for example. Switches SW4, SW5 and SW6 for turning on / off the power supply of the gold code generator 17, the transmission amplifier 18 and the wave transmitter 19 are provided. These switches SW4 to SW6 are controlled by a control signal from the CPU 11.

  Transmission data is supplied to the transmitter 19 via the transmission amplifier 18. The transmitter 19 is a laminate of piezoelectric elements, and generates an ultrasonic wave by applying an alternating voltage (drive signal) to the piezoelectric elements. The generated ultrasonic waves are emitted into the sea. Strong ultrasonic vibration can be generated by applying a drive signal having a resonance frequency of the piezoelectric element. The ultrasonic waves from the transmitter 19 are received by a receiver at a maritime station mounted on a fishing boat. By such transmission and reception, measurement data can be acquired in real time. Therefore, the fishing boat in operation can know the relationship between the measurement data such as water depth and temperature and the catch.

  In addition, a receiver 20 is provided for receiving underwater ultrasonic waves. A reception signal from the receiver 20 is supplied to a signal level identification circuit 22 and a frequency discrimination circuit 23 via a reception amplifier 21. The signal level identification circuit 22 is a circuit for identifying the level of the received signal. Whether the level of the received signal exceeds a preset threshold is identified based on the peak value, average value, or envelope of the received signal. The identification result of the signal level identification circuit 22 is supplied to the CPU 11.

  The frequency discriminating circuit 23 determines whether or not the frequency of the received signal matches (or substantially matches) a predetermined frequency, for example, the frequency f (= 1 / T) of the detection beam 3 of the fish detector. The discrimination result of the frequency discrimination circuit 23 is supplied to the CPU 11. A switch SW7 for turning on / off the power supply of the frequency discrimination circuit 23 is provided. The switch SW7 is controlled by a control signal from the CPU 11. As will be described later, when the signal level identification circuit 22 determines that the level of the received signal exceeds the threshold value, the switch SW7 is turned on by a control signal from the CPU 11.

  The CPU 11 receives the identification result of the signal level identification circuit 22 and the identification result of the frequency discrimination circuit 23, and determines whether the underwater ultrasonic wave received is the detection beam 3 of the fish finder. When the CPU 11 determines that the received ultrasonic wave is the detection beam 3 of the fish finder, the CPU 11 outputs a power control signal for turning on the switches SW1 to SW6. The state where the switches SW1 to SW7 are OFF is the power saving mode, and the state where these are ON is the operation mode. In the power saving mode, power consumption is reduced compared to the operation mode. Note that the switches SW1 to SW7 are configured as semiconductor switches, and a plurality of switches controlled in common may be integrated into a single switch configuration.

  FIG. 3 illustrates an example of a signal waveform. FIG. 3A shows a received signal from the receiving amplifier 21, for example, a received signal corresponding to the detection beam 3. As shown in FIG. 1B, when the underwater sensor 1 receives a detection beam, a received signal having a level equal to or higher than the threshold value TH is obtained. In response to this identification result, the frequency discrimination circuit 23 is powered on as shown in FIG. 3B.

  A frequency discrimination circuit 23 detects the frequency of the detection beam 3 and generates a detection output shown in FIG. 3C. FIG. 3D shows the detection beam 3 in an enlarged manner. The CPU 11 receives the identification output of the signal level identification circuit 22 and the detection output of the frequency discrimination circuit 23, and turns on the switches SW1 to SW6. As a result, the power of the sensor 13, the sensor amplifier 14, the A / D converter 15, the gold code signal generator 17, the transmission amplifier 18, and the transmitter 19 is turned on, and as shown in FIG. Sent.

  As shown in FIG. 3E, since the gold code signal is intermittently transmitted as an ultrasonic wave and the measurement data is transmitted at intervals of the gold code signal, the power required for transmission is less than that in the continuous communication method. The power source, for example, the consumption of the primary battery can be suppressed. Furthermore, since an ID signal can be sent, even when a plurality of underwater sensors are used, there is an advantage that the underwater sensors can be identified.

A mode switching operation performed under the control of the CPU 11 in the embodiment of the present invention will be described with reference to FIG. A series of processing described below is performed with a predetermined cycle, for example.
Step ST1, Step ST2: It is determined whether or not the signal supplied from the signal level identification circuit 22 exceeds a threshold value (TH level). If the signal level of the received signal does not exceed the TH level, the process returns to step ST1.

Step ST3, Step ST4: When it is determined that the signal level of the received signal exceeds the TH level, the frequency discrimination circuit 23 is turned on and the frequency is measured. It is determined whether this frequency matches the frequency f (= 1 / T) of the detection beam 3 of the fish finder. An affirmative determination result may also be used when the frequency substantially matches the frequency f of the detection beam 3 of the fish finder.
Step ST5: When it is determined that the frequency of the received signal does not match the frequency f of the detection beam 3, the power of the frequency discrimination circuit 23 is turned off.

  Step ST6: If it is determined in steps ST3 and ST4 that the frequency of the received signal matches the frequency f of the detection beam 3, the power of the gold code signal generator 17, the transmission amplifier 18 and the transmitter 19 is turned on, and gold A code signal is transmitted.

  Step ST7: It is determined whether or not the transmission is completed. The transmission may be completed when a predetermined time elapses after the transmission of the predetermined signal is completed, or the transmission may be completed by receiving a normal reception response from the maritime station by enabling bidirectional communication with the maritime station.

  Step ST8: When it is determined that the transmission is completed, the powers of the gold code signal generator 17, the transmission amplifier 18 and the transmitter 19 are turned off. Thus, the startup process ends and the power saving mode is restored. And it waits in the state which performs the determination process of step ST1, step ST2.

  A receiving device (for example, a marine station) that receives underwater ultrasonic waves from the underwater sensor 1 will be described with reference to FIG. A reception signal from a wave receiver 31 such as an underwater microphone is supplied to a band pass filter 32, and a necessary band component is separated. The output signal of the bandpass filter 32 is supplied to the ID detection unit 33, and the ID signal is detected.

  The ID signal separated by the ID detection unit 33 is supplied to the data determination unit 34. The data discriminating unit 34 examines the time interval of the ID signal and discriminates different measurement data such as water temperature data and water depth data. The obtained measurement data is supplied to the data processing unit 35. The data processing unit 35 stores measurement data in the memory 36. Further, the data processing unit 35 performs control to display a graph, a chart, and the like indicating the relationship between the water depth and the water temperature on the display unit 37. The data discriminating unit 34 and the data processing unit 35 are configured as a microcomputer including a CPU.

  In addition, when the above-described underwater sensor 1 is pulled up to the sea, a coupling coil and a communication unit for transmitting and receiving data to and from the underwater sensor 1 may be provided. Further, the receiving device preferably has a configuration of a small portable terminal such as a smart phone or a tablet. Further, in the case of a fishing boat, a fish finder 41 is mounted together with the receiving device. The fish detector 41 has a transmitter 42 that transmits a detection beam into the sea and a receiver 43 that receives a reflected beam. The fish detector 41 does not need to be linked with the maritime station, but as described above, the underwater sensor 1 is activated in response to the detection beam of the fish detector 41, so that the fish detector 41 emits the detection beam. It may be linked so that the maritime station is in an operating state only during the period.

  According to an embodiment of the present invention, when the underwater sensor 1 receives underwater ultrasonic waves having a predetermined level and a predetermined frequency, the operation mode is set, and therefore, power consumption (battery) can be suppressed. . In addition, when the underwater sensor 1 is activated to transmit measurement data, it is guaranteed that a fishing boat loaded with a maritime station and a vessel such as a survey vessel are nearby, so transmission is not wasted and measurement is reliably performed. There is an advantage that data can be acquired. Furthermore, in the case of a fishing boat, the underwater sensor 1 can be activated only by performing a normal operation, so that there is an advantage that it does not take extra time and there is an advantage that it is easy to obtain the cooperation of fishermen.

<2. Modification>
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible. For example, a plurality of underwater ultrasonic waves may be received together with the frequency, and the transmission signal processing unit may be activated when the number and / or interval of the underwater ultrasonic waves are predetermined. The configurations, methods, processes, shapes, materials, numerical values, and the like given in the above-described embodiments are merely examples, and different configurations, methods, processes, shapes, materials, numerical values, and the like are used as necessary. Also good. For example, not only a fishing boat but a survey boat may emit a detection beam having a predetermined frequency. Furthermore, the present invention can also be applied to water quality measurements on fresh water surfaces.

1 Underwater sensor 2 Fishing boat 3 Detection beam 11 CPU
13 Sensor 22 Signal level identification circuit 23 Frequency discrimination circuit

Claims (6)

A sensor unit, and a transmission signal processing unit for transmitting measurement data of the sensor unit as underwater ultrasonic waves,
A received signal processing unit having a frequency discrimination circuit that receives underwater ultrasonic waves and determines whether or not the frequency of the received signal substantially matches a predetermined frequency;
An underwater sensor comprising: a control unit that performs control such that the transmission signal processing unit is activated when a determination result of the reception signal processing unit is supplied and a frequency of the reception signal substantially matches a predetermined frequency.   The underwater sensor according to claim 1, wherein the reception signal processing unit turns on the power of the frequency discrimination circuit when the level of the reception signal exceeds a threshold level.   The underwater sensor according to claim 1, wherein the reception signal processing unit turns on the power of the frequency discrimination circuit when the number and / or interval of reception signals are predetermined.   The underwater sensor according to any one of claims 1 to 3, wherein the predetermined frequency substantially matches a frequency of a detection beam of the fish finder.   The underwater sensor according to claim 1, further comprising a memory for storing measurement data or data obtained by processing the measurement data.   The underwater sensor according to any one of claims 1 to 5, wherein the transmission signal processing unit modulates a time interval of an identification signal in accordance with measurement data from the sensor unit.

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